What Size Generator for a CPAP Machine?
Any generator runs a CPAP; the machine itself draws 30 to 60 watts. The numbers that matter are the heated humidifier (add 150 to 250W when it's on) and the hours: a full night is 8 hours of continuous, silence-adjacent, clean power, which is why the honest first recommendation here is a battery power station, with the generator as its daytime charger.
Wattage by type
| CPAP machine type | Running | Starting |
|---|---|---|
| CPAP, humidifier off | 30 to 60 W | no surge |
| CPAP + heated humidifier | 150 to 250 W | no surge |
| CPAP + humidifier + heated hose | 200 to 300 W | no surge |
| BiPAP | 60 to 100 (add humidifier as above) W | no surge |
What it takes with company
Same engine as the wattage picker: running total plus the single biggest start spike, then the smallest class that carries it with 20% headroom.
| Load list | Running | Peak | Buy |
|---|---|---|---|
| CPAP + humidifier alone | 250 W | 250 W | 2,200W inverter |
| CPAP + humidifier + fridge + the basics | 1,150 W | 2,650 W | 3,400W inverter |
The details that change the answer
Run the watt-hours, not the watts. A CPAP with the humidifier off uses about 30 to 60W, so a night is under 500 watt-hours: comfortably inside a mid-size power station, silently, next to the bed, no carbon monoxide within a hundred feet of your airway. Turn the heated humidifier on and the draw quadruples, which halves-to-quarters the battery math; most machines have a non-heated passover mode for exactly this situation, and using it during outages is the single best trick on this page.
Where the generator earns its place is duration. Multi-day outage, the station runs the nights and the generator (already out there for the fridge) recharges it each morning; 500Wh of recharge is about 20 minutes of one refrigerator-scale load. If you'd rather run the CPAP on the generator directly, any inverter unit is enormously oversized for the job and does it fine; use the 12V or DC adapter kit your CPAP maker sells if you want to skip the wall-adapter conversion losses. Talk to your DME supplier about the manufacturer's official battery, too; insurance occasionally covers it.
Questions people ask
How long will a power station run a CPAP?
Divide the station’s watt-hours by your draw: a 500Wh station runs a 45W machine (humidifier off) about 9 to 10 hours after inverter losses, one full night. With a heated humidifier at 200W total it is 2 to 3 hours, which is why humidifier-off is the outage setting. A 1,000Wh station covers two nights dry or one humid night with margin.
Is generator power safe for a CPAP?
From an inverter generator or through a power station, yes; both produce cleaner power than a bad grid day. Cheap open-frame generators with high distortion are the ones to keep away from medical equipment, or buffer with a small UPS. And the machine is at your face all night, so the generator stays its full 20 feet from the house regardless of how nice its sine wave is.
Other single appliances
Every row uses the same planning numbers as the full wattage chart.